Method of making spark wheels for cigar and cigarette lighters



Feb. 27, 1951 DREYER r 2,543,235

ME D OF MAKING SPARK WHEELS FOR I AR AND CIGAR E LIGHTERS Filed Jan. 1950 i W Q0 19 Ti .1 ,/9; =1 19 M 7; INVE- R.

7 WERNER PFLU By EDWARD L. DREYER ATTORNEY Patented Feb. 27, 1951 omen arms METHOD OF" MAKING sPARKwnEELs FOR GIGAR' AND GIGARETTE LIGHTERS Edward lirever, New York, and Werner lfflug. Newark, N. -J., assijg nors to Adarna's Carf bide Corporation, Harrison; N; J a corporation of New Jersey Application Jaiiua'iy 24, 1556', seiial'i it. 140,156

3 Claims.

v This invention relates to methods of makin spark wheels for cigar and cigarette lighters. It

particularly directed to a method of rnaking a 'spark wheel of sintered tungsten carbide.

Heretofore sintered tungsten carbide spark wheels for pyrophoric lighters were provided with knurling at the peripherybygrinding the knurltofore constructed were mounted directly on a supporting shaft therefor and the tungsten carbide wheel being rough would wear away the shaft unless the hole in the wheel was lapped, which is likewise a costly operation.

It is therefore an object of this invention to provide a highly in ipro'ved process for making 'sintered tungsten carbid spark: wheels comprising molding oi tungsten carbide piowder with ratchet teethon one side ror turning the wheel, thereafter presintering the wheel, thereafter "grinding the knurling on the outer surface of r the wheel, and thereafter putting the wheel 'through a final sinteringprocess. The grinding of th knurling on the wheel between rre re- "sirrteri'ng and f nal sintering process makes it easier and less expensive to grind.

A further objector this invention is to provide a highly improved method of making a spark whe of he e ere e o en er iif ii e we bide and providing the same with a bushing insort of a metal such steel or brass which is not as hard as the wheel itself, so that such a bushing will riot wear away the shaft and does not require to be lapped. e M

Yet a fiirther object of this invention is to provide a sintered s are wheel of the character described having knurling made of pr irnary outs running from longitiidinal with the axis of the wheel to 45 degrees with the longitudinal and thereafter cutting or grinding secondary transverse or peripheral cuts from a plane perpendicular to the axis to a plane 45 degrees with the perpendicular, whereby the longitudinal teeth are broken up by the transverse or peripheral cuts and it being a further object of this invention to make the transverse or peripheral cuts of less depth than the longitudinal cuts.

The cuts may either be V shaped or ratchet typ'e an'd' the rake of the teeth may be either positive'or negative or zero on one side. p

another object of this invention is to provide a spark wheel of'the characterdes'cribed in which thebushing is knurl d on the outside and therr forced into the cen al opening in the "si-nte'redtungsten carbide spark wheel causing the hard tungsten carbide to shave oiT some of partioulafiy to state when r 2 p the knurling of the bushing for rigidly attaching the bushing to the wheel so that the two will "rotate together.

S till another object of this invention is to 'provide 'a strong and durable article of the character described which will be relatively inexpensive to rnanufa cture and which shall yet be practical and efiicient to a high degree iniise. A still furtherobject of this invention is to provide a highly improved and economic process 'ior'r'rra-king spark wheels of the character de scribed. V

r Other objects or this invention will in part be obviousand in part hereinafter pointed out.

The invention accordingly consists in the feaes of construction, combinations of elements,

' ena-ea-asgemem of parts, which will be exernplified in the construction hereinafter described, and oi which the scope of invention will be indicated inthe following claims: I v e the accompanying drawings which is shown va'rious illustrative embodiments of this inrs n lfi'g. 1 top plan view of a spark wheel showing t e range after the rnolding of the tungsten oar 1 e powder or after the presintering furnace e p H 21 .1%. i912 ee Vi i. the h e Shown in Fig. 1 and showing the same after the longihave been ground therein, after the presinte'ring furnace stage and before the final furnace stage;

Fig. 3 is s top can view of the wheel shown in I Fig. 2 after the transverse cuts have been ground therein;

Fig. 4 "is atop plan view of the spark wheel with the bushing inserted therein;

Fig. 5 is a top' plan view of the bushing before it i 'finserted into the wheel;

Fig, 6 is a side elevational view of the bushing;

Fig. '7 is a front elevati'onal view of the structure shown in Fig. 4;

Fig 8 is a partial cross sec ional view taken on line 8. 8 of 1;

Fig. 9 is a partial cross-sectional view taken on line 9 s of Fig. 2;

Fig. 10 is" a ci'oss sectional View taken on line view taken on line taken on line ferri'ng now in'detail to the drawing. and.

e. 1a an 1e. 1e designates invreprior e-ligmers. reesame therein. The Wheel H is made of sintered tungsten carbide. It is formed with an axial through opening 13 at its one fiat annular surface [6. The surface thereof opposite surface [6 is formed with ratchet teeth 11. At its periphery the wheel H is formed with longitudinal V shaped grooves l9 which are inclined to the axis of the wheel. The grooves l9 may have any angle from zero to an angle of about 45 degrees with the longitudinal axis. The grooves [9 form longitudinal teeth between the grooves. The longitudinal teeth 20 each have a leading surface 2| which is either radial or has a positive or negative rake. Earh tooth 20 has an oppositely inclined surface 22 which is tangent to a circle having an axis at the axis of the wheel.

The periphery of the wheel is furthermore formed with a plurality of peripheral or transverse grooves 25 which may be V shaped. The direction of the grooves 25 is shown in Fig. 4 as at an angle to the axis of the wheel. Said grooves may lie in a plane from perpendicular to the axis to an angle of about 45 degrees with the perpendicular to the axis.

It will be noted that the grooves I 9 are parallel to one another and that the grooves 25 are likewise parallel to one another particularly the grooves 25 are not as deep as the grooves l9 they may be about one-half as deep. It will be noted that each longitudinal tooth 20 is divided by the grooves 25 into a series of teeth 21. The grooves l9 and 25 may be made by grinding in accordance with the method to be described hereinafter.

The bushing l2 may be made of steel or brass or any other metal which is not as hard as the sintered tungsten carbide of which the wheel II is made. The bushing [2 has an axial through opening 30. It is formed with an outer longitudinal knurled surface 3|, one end of which may be beveled as at 32. Extending from one side of the enlarged portion 3! is a reduced flange 33. The diameter of the outside of the teeth of the knurling 3| is somewhat greater than the diameter of the opening [3 of the Wheel H. The bushing is forced into the wheel so that the knurling 3| scrapes against the inner surface l3 and some of the knurling is shaved off and the teeth become firmly wedged in the inner surface l3 to firmly secure the bushing to the wheel. It will be noted that one end wall 34 of the enlarged portion of the bushing is substantially fiush with the side surface l6 of the wheel. The width of the head or enlarged portion 3| is less than the width of the wheel but the flange 33 extends beyond the ratchet teeth I! as shown in Fig. 14 of the drawing.

The method of making the spark wheel will now be described. The tungsten carbide is first molded to form the wheel A shown in Fig. 1. The wheel A has a smooth outer surface 40 and the side surface [6. It is also molded with integral ratchet teeth I"! at the opposite side. It is also formed with molded through opening l3. The piece A is then placed in a presintering furnace which is heated to between 600 and 900 degrees centigrade. in the usual manner. After the presintering stage the longitudinal grooves [9 are ground to form the teeth 20 thereby formingthe device B, shown in Fig. 2. Thereafter the wheel is ground transversely to form the V shaped grooves 25, thereby forming the piece C, shown in Fig. 3. Thereafter the device C is placed in a final sintering furnace which is heated to from 1400 to 1550 degrees centigrade. After the final sintering stage the bushing 12 is forced into the opening [3 to form the final device Hi.

It will be understood that the knurling at the outside of the wheel is ground after the presintering stage and before the final sintering stage. If the knurling were ground after the final sintering stage diamond grinding wheel would be necessary thereby increasing the cost of the device. Furthermore it will be noted that the bushing will form a good bearing for the shaft on which the wheel rotates as it is not as rough as the tungsten carbide of which the wheel is made and the inner surface 3!. of the bushing need not be lapped. It has been found that by grinding the longitudinal grooves [9 at an angle to the longitudinal and the transverse or pheripheral grooves 25 at an angle to a plane perpendicular to the axis a highly efficient spark wheel is obtained and this is particularly true when making the grooves 25 of less depth than the grooves I9.

It will thus be seen that there is provided a device in which the several objects of this invention are achieved and which is well adapted to meet the conditions of practical use.

As various possible embodiments might be made of the above invention, and as various changes might be made in the embodiment above set forth, it is to be understood that all matter herein set forth or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.

Having thus described our invention we claim as new and desire to secure by Letters Patent:

1. A process for making a spark wheel comprising molding tungsten carbide powder to form a wheel with ratchet teeth at one side, thereafter heating the wheel in a presintering furnace, thereafter grinding knurling in the outer surface of the wheel, and thereafter heating the wheel in a final sintering furnace at a higher temperature than in the presintering furnace.

2. A process of the character described comprising molding tungsten carbide powder to form a wheel, then presintering the wheel, then grinding knurling in the exterior surface of the wheel,

and then heating the wheel in a final sintering furnace at a temperature higher than the presintering stage.

3. A process of the character described comprising molding tungsten carbide powder to form a wheel having a central through opening and ratchet teeth at one side, then treating the wheel in a presintering furnace at a heat from 600 to 900 degrees centigrade, thereafter grinding longitudinal grooves in the outer periphery of the wheel, thereafter grinding transverse grooves in the outer periphery of the wheel and thereafter treating the wheel in a final sintering furnace at a temperature of from 1400 to 1550 degrees centigrade.

EDWARD L. DREYER. WERNER PFLUG.

REFERENCES CITED The following references are of record in the file ofv this patent:

' UNITED STATES PATENTS Number Name Date 1,951,133 De Bats Mar. 13, 1934 7 2,286,672 De Lamatter June 16, 1942 2,303,304 Schleicher et al. Nov. 24, 1942 2,443,123 S olon June 8, 1948 

